/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

// Contributors:  Kitching Simon <Simon.Kitching@orange.ch>
//                Nicholas Wolff

package org.apache.log4j;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.ObjectStreamException;
import java.io.Serializable;

/**
 * Defines the minimum set of levels recognized by the system, that is
 * <code>OFF</code>, <code>FATAL</code>, <code>ERROR</code>, <code>WARN</code>,
 * <code>INFO</code, <code>DEBUG</code> and <code>ALL</code>.
 * 
 * <p>
 * The <code>Level</code> class may be subclassed to define a larger level set.
 * 
 * @author Ceki G&uuml;lc&uuml;
 */
public class Level extends Priority implements Serializable {

	/**
	 * TRACE level integer value.
	 * 
	 * @since 1.2.12
	 */
	public static final int TRACE_INT = 5000;

	/**
	 * The <code>OFF</code> has the highest possible rank and is intended to
	 * turn off logging.
	 */
	final static public Level OFF = new Level(OFF_INT, "OFF", 0);

	/**
	 * The <code>FATAL</code> level designates very severe error events that
	 * will presumably lead the application to abort.
	 */
	final static public Level FATAL = new Level(FATAL_INT, "FATAL", 0);

	/**
	 * The <code>ERROR</code> level designates error events that might still
	 * allow the application to continue running.
	 */
	final static public Level ERROR = new Level(ERROR_INT, "ERROR", 3);

	/**
	 * The <code>WARN</code> level designates potentially harmful situations.
	 */
	final static public Level WARN = new Level(WARN_INT, "WARN", 4);

	/**
	 * The <code>INFO</code> level designates informational messages that
	 * highlight the progress of the application at coarse-grained level.
	 */
	final static public Level INFO = new Level(INFO_INT, "INFO", 6);

	/**
	 * The <code>DEBUG</code> Level designates fine-grained informational events
	 * that are most useful to debug an application.
	 */
	final static public Level DEBUG = new Level(DEBUG_INT, "DEBUG", 7);

	/**
	 * The <code>TRACE</code> Level designates finer-grained informational
	 * events than the <code>DEBUG</code level.
	 * 
	 * @since 1.2.12
	 */
	public static final Level TRACE = new Level(TRACE_INT, "TRACE", 7);

	/**
	 * The <code>ALL</code> has the lowest possible rank and is intended to turn
	 * on all logging.
	 */
	final static public Level ALL = new Level(ALL_INT, "ALL", 7);

	/**
	 * Serialization version id.
	 */
	static final long serialVersionUID = 3491141966387921974L;

	/**
	 * Instantiate a Level object.
	 */
	protected Level(int level, String levelStr, int syslogEquivalent) {
		super(level, levelStr, syslogEquivalent);
	}

	/**
	 * Convert the string passed as argument to a level. If the conversion
	 * fails, then this method returns {@link #DEBUG}.
	 */
	public static Level toLevel(String sArg) {
		return (Level) toLevel(sArg, Level.DEBUG);
	}

	/**
	 * Convert an integer passed as argument to a level. If the conversion
	 * fails, then this method returns {@link #DEBUG}.
	 */
	public static Level toLevel(int val) {
		return (Level) toLevel(val, Level.DEBUG);
	}

	/**
	 * Convert an integer passed as argument to a level. If the conversion
	 * fails, then this method returns the specified default.
	 */
	public static Level toLevel(int val, Level defaultLevel) {
		switch (val) {
		case ALL_INT:
			return ALL;
		case DEBUG_INT:
			return Level.DEBUG;
		case INFO_INT:
			return Level.INFO;
		case WARN_INT:
			return Level.WARN;
		case ERROR_INT:
			return Level.ERROR;
		case FATAL_INT:
			return Level.FATAL;
		case OFF_INT:
			return OFF;
		case TRACE_INT:
			return Level.TRACE;
		default:
			return defaultLevel;
		}
	}

	/**
	 * Convert the string passed as argument to a level. If the conversion
	 * fails, then this method returns the value of <code>defaultLevel</code>.
	 */
	public static Level toLevel(String sArg, Level defaultLevel) {
		if (sArg == null)
			return defaultLevel;

		String s = sArg.toUpperCase();

		if (s.equals("ALL"))
			return Level.ALL;
		if (s.equals("DEBUG"))
			return Level.DEBUG;
		if (s.equals("INFO"))
			return Level.INFO;
		if (s.equals("WARN"))
			return Level.WARN;
		if (s.equals("ERROR"))
			return Level.ERROR;
		if (s.equals("FATAL"))
			return Level.FATAL;
		if (s.equals("OFF"))
			return Level.OFF;
		if (s.equals("TRACE"))
			return Level.TRACE;
		//
		// For Turkish i problem, see bug 40937
		//
		if (s.equals("\u0130NFO"))
			return Level.INFO;
		return defaultLevel;
	}

	/**
	 * Custom deserialization of Level.
	 * 
	 * @param s
	 *            serialization stream.
	 * @throws IOException
	 *             if IO exception.
	 * @throws ClassNotFoundException
	 *             if class not found.
	 */
	private void readObject(final ObjectInputStream s) throws IOException,
			ClassNotFoundException {
		s.defaultReadObject();
		level = s.readInt();
		syslogEquivalent = s.readInt();
		levelStr = s.readUTF();
		if (levelStr == null) {
			levelStr = "";
		}
	}

	/**
	 * Serialize level.
	 * 
	 * @param s
	 *            serialization stream.
	 * @throws IOException
	 *             if exception during serialization.
	 */
	private void writeObject(final ObjectOutputStream s) throws IOException {
		s.defaultWriteObject();
		s.writeInt(level);
		s.writeInt(syslogEquivalent);
		s.writeUTF(levelStr);
	}

	/**
	 * Resolved deserialized level to one of the stock instances. May be
	 * overriden in classes derived from Level.
	 * 
	 * @return resolved object.
	 * @throws ObjectStreamException
	 *             if exception during resolution.
	 */
	private Object readResolve() throws ObjectStreamException {
		//
		// if the deserizalized object is exactly an instance of Level
		//
		if (getClass() == Level.class) {
			return toLevel(level);
		}
		//
		// extension of Level can't substitute stock item
		//
		return this;
	}

}
